Seasonal egg production of whitemouth croaker, Micropogonias furnieri, of the Rio de la Plata estuary, Argentina-Uruguay

MACCHI, G. J.; ACHA, M.; MILITELLI, M.

Fishery Bulletin

Año: 2003 vol. 101 p. 332 - 342

0090-0656

The reproductive biology of the whitemouth croaker, Micropogonias furnieri, inhabiting the estuarine waters of the Río de la Plata (Argentina-Uruguay) was studied by using histological analysis of the ovaries. Samples were collected during the spawning peak and the end of two breeding seasons (November 1995 - February 1996 and November 1997 - March 1998). Micropogonias furnieri is a multiple spawner with indeterminate annual fecundity. Spawning frequency, determined using the percentage of females with postovulatory follicles, was about 31 % in November 1995 and 25 % in February 1996. At these frequencies, a female on average spawned a new batch of eggs every 3 - 4 days during the spawning season. Batch fecundity was fitted to a power function of length and a linear function of ovary-free female weight. The number of hydrated oocytes decreased at the end of the breeding season, coinciding with an increase of atresia. Annual egg production for a 40-cm-TL female was estimated to be between 3,300,000 and 7,300,000 eggs. In addition to the seasonal decrease in fecundity and spawning activity, a decline in egg size and weight toward the end of the breeding season was also observed.